//反转一个单链表。 
//
// 示例: 
//
// 输入: 1->2->3->4->5->NULL
//输出: 5->4->3->2->1->NULL 
//
// 进阶: 
//你可以迭代或递归地反转链表。你能否用两种方法解决这道题？ 
// Related Topics 链表


package leetcode.d_200_299;

//Java：反转链表
public class P206ReverseLinkedList{
    public static void main(String[] args) {
        Solution solution = new P206ReverseLinkedList().new Solution();
        // TO TEST
    }
    //leetcode submit region begin(Prohibit modification and deletion)
    /**
     * Definition for singly-linked list.
     * public class ListNode {
     *     int val;
     *     ListNode next;
     *     ListNode(int x) { val = x; }
     * }
     */
    class Solution {
        public ListNode reverseList(ListNode head) {
            if (head == null){
                return head;
            }
            ListNode pre = null;
            ListNode cur = head;
            while (cur != null){
                ListNode nextTemp = cur.next;
                cur.next = pre;
                pre = cur;
                cur = nextTemp;
            }
            return pre;
        }
    }
//leetcode submit region end(Prohibit modification and deletion)

}